The present invention relates to a flat panel display of the type which includes focusing guides for maintaining electrons which are injected thereinto in confined beams, and particularly to focusing guides which includes means for extracting widely divergent electrons from said beams at the injection ends of their respective guides.
There has been developed a flat panel display which includes an evacuated envelope having a substantially rectangular display section and a gun section extending along at least one edge of the display section. The display section includes opposed front and back walls and spaced, parallel support walls extending between the front and back walls. The support walls are arranged to form therebetween channels which open at one end into a gun section. A phosphor screen extends across the inner surface of the front wall. The gun section contains a gun structure which is adapted to generate electrons and direct the electrons as beams along each of the channels. There is at least one beam for each channel. Along the channels are focusing guides through which the electron beams flow. There is one focusing guide for each electron beam. The focusing guides serve to confine the electrons in the beam along the entire length of the channel. The focusing guides also include means for deflecting the beams out of the guide toward the phosphor screen at spaced points along the length of the channels so as to achieve line-by-line scan of the phosphor screen. Such a display is described in the application for U.S. Pat. of T. O. Stanley, Ser. No. 670,492, filed Aug. 25, 1975, entitled "Flat Electron Beam Addressed Device".
There are several types of focusing guides which can be used in the above flat panel display. One type of focusing guide is described in the application for U.S. Pat. of T. L. Credelle, Ser. No. 607,490, filed Aug. 25, 1975, entitled "Flat Display Device With Beam Guide" hereinafter described in detail.
Another type of focusing guide is described in the application for U.S. Pat. of W. W. Siekanowicz et al., Ser. No. 671,358, filed Mar. 29, 1976, entitled "Flat Display Device With Beam Guide" hereinafter described in detail.
No matter what type of focusing guide is used, it is desirable to have all of the electrons injected into the guide travel the length of the guide without hitting any of the parts of the guide. This will provide the highest uniformity of brightness at each point of extraction along the guide. Although it may be possible to have a gun structure of such precision that it will inject all of the electrons into the guide in such a manner as to cause all electrons to so travel along the guide, such a gun would be difficult and expensive to make. Therefore, it would be desirable to be able to achieve this result in some other manner which is simpler and less expensive.